Using Microsoft Teams on macOS, including installation, features, and compatibility
Good day Tim,
The old accounts appear because their credentials are still saved in macOS Keychain. Please also ensure that both the operating system and the Teams app are updated to the latest versions.
To remove an old account:
Quit Microsoft Teams completely.
Open Finder > Applications > Utilities > Keychain Access.
Find the account you no longer use.
Right click the account and select Delete.
Reopen Teams and check whether the account has been removed from the sign in list.
Please note that deleting an account from Keychain can also affect other Microsoft apps that use the same account.
After that, clear the Teams cache by following the steps in this article: Clear the Teams client cache - Microsoft Teams | Microsoft Learn
To add your preferred account:
Open Microsoft Teams > Select your profile picture > Select Add another account.
Select Create or use another account if the account isn't listed.
Enter the account credentials and complete the sign in process.
If the account still doesn't appear, sign out of Teams, reopen the app, and sign in directly with the account you want to use.
I hope this helps. If you have any questions or need further support, please don’t hesitate to reach out at any time.
Thank you for your patience and understanding.
If you have any extra questions about this answer, please click "Comment".